Density correlations in a many particle system

Takafumi Kita

A. Gonis, T. C. Schulthess, Jan van Ek +1 more

It is shown that interacting many-particle quantum systems can be described in terms of fully correlated $n$-particle densities, which determine uniquely the potential acting on the system and satisfy a minimum principle with respect to the ground-state energy. This leads to a generalization of ordinary density functional theory in terms of $n$-particle densities which allows the direct and self-consistent treatment of correlation effects within electronic structure methods for atoms, molecules, and solids.

Jean-Louis Basdevant, Jean Dalibard

V. I. Gerasimenko

The paper deals with the problem of the rigorous description of the evolution of states of large particle quantum systems by means of correlation operators. A nonperturbative solution of the Cauchy problem of the hierarchy of nonlinear evolution equations for a sequence of marginal correlation operators is constructed. For initial states specified in terms of a one-particle density operator and correlation operators we also develop an approach to the description of the processes of the creation and the propagation of correlations within the framework of a one-particle density operator. Moreover, the mean field asymptotic behavior of constructed marginal correlation operators is established.

Fa Yueh Wu

A closed expression similar to the Ursell-Mayer expansion is obtained for the static multiple density correlation function In=〈ρk1⋯ρkn〉 of a many-particle system. It is shown that In breaks into products of lower ones, if there exist partial momentum conservations among the k's. Using the convolution approximation for the n-particle correlation function, we evaluate In in a closed form. The result is shown to be accurate in the small k region.